How to Calculate Your RMD: The Math Behind Required Minimum Distributions
For the broader RMD context, start with RMD Planning: The Complete Guide. This piece focuses specifically on the math — formulas, tables, worked examples at different ages and account sizes, and the edge cases that complicate the first RMD year.
The basic formula
RMD = Prior year-end account balance ÷ Life expectancy factor
Two inputs, deceptively simple:
Prior year-end account balance. The fair market value of the account on December 31 of the year preceding the RMD year. For your 2026 RMD, the balance is what the account was worth on December 31, 2025. This is what your custodian reports on Form 5498 and reflects in their RMD calculations.
Life expectancy factor. Comes from one of three IRS tables, chosen based on your situation and relationship to the account.
The three tables
Uniform Lifetime Table
The default for most account owners. Used if:
- You’re a single account owner, or
- Your spouse is not the sole beneficiary, or
- Your spouse is the sole beneficiary but not more than 10 years younger than you
This table covers the vast majority of RMD calculations. Factors reflect joint life expectancy of you and a hypothetical beneficiary 10 years younger, which produces smaller RMDs than using your life expectancy alone would.
Representative factors:
| Age | Factor | % of balance |
|---|---|---|
| 73 | 26.5 | 3.77% |
| 74 | 25.5 | 3.92% |
| 75 | 24.6 | 4.07% |
| 76 | 23.7 | 4.22% |
| 77 | 22.9 | 4.37% |
| 78 | 22.0 | 4.55% |
| 79 | 21.1 | 4.74% |
| 80 | 20.2 | 4.95% |
| 81 | 19.4 | 5.16% |
| 82 | 18.5 | 5.41% |
| 83 | 17.7 | 5.65% |
| 84 | 16.8 | 5.96% |
| 85 | 16.0 | 6.25% |
| 86 | 15.2 | 6.58% |
| 87 | 14.4 | 6.94% |
| 88 | 13.7 | 7.30% |
| 89 | 12.9 | 7.76% |
| 90 | 12.2 | 8.20% |
| 92 | 10.8 | 9.26% |
| 95 | 8.9 | 11.24% |
| 100 | 6.4 | 15.63% |
For current complete table, see IRS Publication 590-B.
Joint and Last Survivor Table
Used when:
- Your spouse is the sole beneficiary of the account, AND
- Your spouse is more than 10 years younger than you
Factors come from a two-dimensional table based on both your age and your spouse’s age. Because the expected payout period covers two lives — one of which is significantly longer — factors are larger, producing smaller RMDs.
Example: An account owner age 75 with a spouse age 60 (sole beneficiary, 15 years younger). Joint and Last Survivor factor: 29.3. Compared to the Uniform Lifetime factor of 24.6 at age 75, the RMD is about 16% smaller.
The table is large — it covers every combination of ages — but the rule of thumb holds: meaningful age gap + spouse sole beneficiary = smaller RMDs.
Single Life Table
Used by beneficiaries of inherited IRAs, not by original account owners. Factors are smaller than the Uniform Lifetime Table, producing larger RMDs. Covered in detail in Inherited IRA RMD Rules for 2026.
Worked examples
Example 1: Traditional IRA owner, age 73
Balance on December 31, 2025: $750,000. Owner turns 73 in 2026. No spouse beneficiary or spouse within 10 years.
- Table: Uniform Lifetime
- Factor: 26.5
- 2026 RMD: $750,000 ÷ 26.5 = $28,302
Example 2: Traditional IRA owner, age 80
Balance on December 31, 2025: $900,000. Owner turns 80 in 2026. Same filing status.
- Table: Uniform Lifetime
- Factor: 20.2
- 2026 RMD: $900,000 ÷ 20.2 = $44,554
Notice the age effect. Between 73 and 80, the RMD percentage nearly doubled. A larger account combined with an older age produces substantially larger required withdrawals.
Example 3: Traditional IRA owner, age 76, with younger spouse
Balance on December 31, 2025: $750,000. Owner turns 76 in 2026. Spouse is sole beneficiary, age 60 (16 years younger).
- Table: Joint and Last Survivor
- Factor: 28.2 (from IRS Table II, owner age 76 intersected with spouse age 60)
- 2026 RMD: $750,000 ÷ 28.2 = $26,596
For comparison, the Uniform Lifetime Table would have produced $750,000 ÷ 23.7 = $31,646. The younger-spouse provision saves this couple about $5,050 in required distribution for 2026.
Example 4: Multiple traditional IRAs
Same owner, age 73, but with multiple accounts:
- Fidelity traditional IRA: $400,000 year-end balance
- Schwab rollover IRA: $300,000 year-end balance
- Self-directed SEP IRA: $50,000 year-end balance
- Total: $750,000
Aggregate RMD calculation:
- Combined balance: $750,000
- Factor: 26.5
- Total 2026 RMD: $28,302
This $28,302 can be withdrawn from any single IRA or any combination. A common choice: withdraw the full amount from the IRA with the least desirable holdings, or the one where rebalancing is most needed. Or take proportional amounts from each if simpler operationally.
Example 5: Traditional IRA + 401(k), still working
Same owner, age 73, with:
-
Traditional IRA: $750,000
-
Current employer 401(k): $400,000 (still actively employed, not a 5%+ owner)
-
IRA RMD: $750,000 ÷ 26.5 = $28,302 (required)
-
401(k) RMD: $0 (still-working exception applies to current employer plan)
The still-working exception eliminates 401(k) RMDs from the current employer’s plan while still employed. If the owner retires in July 2026, the 401(k) becomes subject to RMDs starting in 2026 (the year of retirement), with the first distribution due by April 1, 2027.
Example 6: First RMD timing pitfall
Owner turns 73 on August 15, 2026. First RMD due for 2026, can be taken by April 1, 2027.
Choice A: Take 2026 RMD in December 2026.
- One RMD in calendar year 2026 ($28,302)
- Second RMD due December 31, 2027 (based on 12/31/2026 balance, age 74 factor 25.5)
Choice B: Delay 2026 RMD until March 2027 (under the April 1 deadline).
- Zero RMD in calendar year 2026
- Two RMDs in calendar year 2027:
- 2026 RMD: $28,302 (taken in March 2027)
- 2027 RMD: based on 12/31/2026 balance, age 74 factor 25.5
- Combined RMDs could exceed $55,000 in a single tax year
For most retirees, Choice A produces a smoother tax picture. Choice B can make sense if you have a specific reason to defer 2026 income into 2027 (low-income year, planned charitable deduction, etc.), but the default advice is to take the first RMD in its actual year.
Annual progression — same account, aging owner
Illustrating how RMDs evolve year over year for a $750,000 traditional IRA with 6% annual growth after the RMD:
| Age | Year-end balance | Factor | RMD that year |
|---|---|---|---|
| 73 | $750,000 | 26.5 | $28,302 |
| 74 | $764,000 | 25.5 | $29,961 |
| 75 | $778,000 | 24.6 | $31,626 |
| 78 | $817,000 | 22.0 | $37,125 |
| 80 | $840,000 | 20.2 | $41,568 |
| 83 | $870,000 | 17.7 | $49,167 |
| 85 | $882,000 | 16.0 | $55,129 |
| 90 | $872,000 | 12.2 | $71,469 |
RMDs grow because the factor decreases faster than the account depletes. Even with positive investment returns, the required percentage eventually dominates — at age 95, roughly 11% of the account must come out each year, exceeding all but the strongest investment returns. The account depletes in real terms once RMDs outpace growth, usually in the mid-80s for typical portfolios.
Common calculation edge cases
Rollovers during the RMD year. If you roll a 401(k) into an IRA during an RMD year, the RMD from the 401(k) must be taken before the rollover. You cannot roll over RMD dollars to an IRA — doing so creates an excess contribution that triggers its own penalty. Custodians typically catch this, but not always.
Conversions during the RMD year. Same rule. If you’re converting traditional IRA money to Roth and you’re past RMD age, take the RMD first, then convert from the remaining balance. The RMD amount itself cannot be converted.
Account opened mid-year. Your first RMD is based on the December 31 balance of the prior year. An account opened January 1, 2026 has no 2026 RMD — the prior year-end balance is $0. Your first RMD would be for 2027, based on December 31, 2026 balance.
Account closed during the year. If you take all the money out of an account (full distribution), you’ve satisfied any RMD for the year in the process. No separate RMD required beyond the full distribution.
Market timing mid-year. RMDs are calculated on December 31 balance of the prior year — not on the balance when you take the distribution. Major market moves during the RMD year don’t change the required amount for that year, though they affect next year’s calculation.
Spouse is only a partial beneficiary. Joint and Last Survivor Table only applies if the spouse is the sole beneficiary. If children are named as partial beneficiaries alongside the spouse, you use the Uniform Lifetime Table even if the spouse is much younger.
What to do once you’ve calculated
Your custodian probably calculated the same number, sometimes with small differences around rounding or starting balance interpretation. Reconcile any discrepancy before acting.
Take the RMD in whatever form makes sense — cash to a checking account, securities transferred in-kind to a taxable account, or direct-to-charity as a QCD (satisfying the RMD without creating taxable income). The QCD Playbook for Retirees covers QCD mechanics in detail.
Withholding: RMDs are subject to default 10% federal income tax withholding; most custodians allow you to adjust this up or down, or to waive withholding if you prefer to pay taxes through quarterly estimates or other means. For many retirees, matching withholding to actual tax liability for the RMD (usually 12–24% federal depending on bracket) simplifies April tax reconciliation.
Try Tempus
Let Tempus do the math — every year, every account
Enter your accounts and current age; Tempus pulls the right table, applies the right factor, and projects your RMD year by year through age 95. Pro tier models the impact of Roth conversions, QCDs, and still-working exceptions on your required-distribution trajectory.
Open Tempus →Frequently asked questions
Do the life expectancy factors ever change?
Yes, periodically. The IRS last updated the tables in 2022, based on longer life expectancy data. The 2022 update made factors larger (smaller RMDs) across the board. Another update is possible in future years but not on a fixed schedule. Use whichever version of the table is current in the year of your RMD.
What balance do I use if I had money in transit between accounts on December 31?
The balance should reflect where the money actually was on December 31. If a transfer initiated in December but not completed until January, the funds were still in the sending account on December 31 and count toward that account's balance. Custodians handle this automatically in their reporting; unusual situations (physical check in the mail, for example) may require manual adjustment with tax advisor guidance.
Do I need to calculate RMDs separately for each IRA or combine them?
For IRAs (traditional, rollover, SEP, SIMPLE), you calculate each one separately, add them up for a total RMD, and can satisfy that total from any single IRA or combination. For 401(k) and similar employer plans, each plan's RMD must come from that specific plan — no aggregation across plans or between plans and IRAs.
Can I use a different IRS table than the default if I want to?
No. The table is dictated by your situation. If your spouse is sole beneficiary and more than 10 years younger, you use Joint and Last Survivor. Otherwise you use Uniform Lifetime (for owners) or Single Life (for inherited IRAs). Picking a different table than your circumstance allows is a calculation error that triggers underpayment penalties.
What if my account had a custodial error and the December 31 balance was wrong?
Work with your custodian to correct the error and document the correct balance. RMD calculations are based on actual fair market value, not what the statement showed. If the custodian already calculated RMD on the wrong balance, adjust the distribution amount before taking it, or take a corrective distribution if you already received too little.
Are RMDs due on Roth IRA balances?
Not during the original owner's lifetime. Roth IRAs have no RMD requirement for the person who established the account. Beneficiaries of inherited Roth IRAs are subject to the 10-year rule or EDB rules, depending on their classification, but without the ordinary income tax that traditional-IRA distributions carry.
What if I have both a traditional IRA and a traditional 401(k)?
Calculate and satisfy each separately. The traditional IRA RMD can be taken from any IRA you own, but the 401(k) RMD must come from that specific 401(k). You cannot use an IRA withdrawal to satisfy a 401(k) RMD, or vice versa.
Does the RMD calculation account for expected investment returns during the year?
No. RMD is based on prior year-end balance only. This simplifies the math but creates some timing effects. An account that grew significantly during the year won't see larger RMDs until the following year. An account that dropped won't see smaller RMDs until the following year. This is why market timing mid-RMD-year doesn't help much — the current year is already locked in.
Can I take my RMD in monthly installments?
Yes, from most custodians. You can set up monthly, quarterly, or other schedules that sum to the annual RMD. Some retirees prefer monthly for budgeting smoothness; others prefer a single annual distribution for simplicity. Either way, the total distributed during the calendar year must meet the RMD threshold.
If I missed an RMD in a prior year, how do I fix it?
Take the missed amount as soon as you can. File IRS Form 5329 for the year of the missed RMD to report the missed distribution and request penalty waiver. Under current rules, the penalty is 25% of the missed amount, reduced to 10% if you correct within two years. Documentation of the mistake (custodian error, misunderstanding, etc.) and prompt corrective action give the IRS discretion to reduce or waive the penalty entirely.
Sources
Chris Gammill is the founder of Ignis Tools and writes about tax-aware retirement planning. Research and drafting assisted by AI tools; all figures and claims verified by the author against primary sources.
- IRS Publication 590-B — Distributions from Individual Retirement Arrangements — retrieved 2026-04-20
- IRS — Retirement plan and IRA Required Minimum Distributions FAQs — retrieved 2026-04-20
- IRS — Uniform Lifetime Table for calculating RMDs — retrieved 2026-04-20